Repairs: roofs and rainwater goods
Problem 1: Moss and lichen
Both clay and concrete tiled roofs are prone to a build up of moss or lichens – particularly concrete tiles that have a rough aggregate surface where fine material is bonded onto the surface of the tile, which provides an idea anchor for moss growth.
A significant build up of moss can increase the weight of the tile by holding a large amount of water; a moderate build up of moss is unlikely to significantly affect any loading values onto the roof.
Solution
If the growth of moss or lichen is a problem it can be addressed with chemical treatment, but this requires significant health and safety precautions to dispose of any run-off and to prevent contamination to flora and fauna within the garden or soakaways.
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Lightning-quick way to prevent moss An effective way to prevent this problem is to bond strips of copper wire across the roof surface. As it becomes wetted down by the weather the copper provides a copper salt wash over the roof surface, providing a low level toxic herbicide to prevent moss growth obtaining a foothold. (Strips of thin lightning conductor material strapped along the ridgeline are reasonably effective.) However, although straightforward, clients seem reluctant to adopt this measure. |